Kevin Plank is not ly­ing. The CEO of Un­der Ar­mour wants to in­vest $4.4 billion in Port Cov­ing­ton, but says he needs $1.2 billion in city, state and fed­eral sub­si­dies (“public in­vest­ments”) for this to make sense. This is God’s truth.

The prob­lem is the po­tent in­vest­ment re­pel­lent that is Bal­ti­more’s prop­erty tax rate. Ac­cord­ing to Mr. Plank’s plan, Port Cov­ing­ton will even­tu­ally have an as­sessed value of $2.6 billion, putting him on the hook for $59 mil­lion in an­nual prop­erty taxes.

If, in­stead, he built a sim­i­lar project in Bal­ti­more County, his tax bill would fall by $30 mil­lion. Every year. For­ever.

This tax gap has fu­eled sub­ur­ban sprawl and ur­ban de­cay for decades — and has dis­parate im­pact on Bal­ti­more’s ma­jor­i­tymi­nor­ity pop­u­la­tion. Just in Fred­die Gray’s trag­i­cally short life, the city lost 111,000 jobs and 164,000 res­i­dents.

Blame “struc­tural racism” for this if you want, but here’s an in­con­ve­nient truth: Even if we waved a magic wand and elim­i­nated all racism to­mor­row — as won­der­ful as that would be — it still wouldn’t make fi­nan­cial sense to de­velop real prop­erty in Sand­town-Winch­ester or, in­deed, most of Bal­ti­more.

This is why every ma­jor rede­vel­op­ment project since Charles Cen­ter in the ’60s has been sub­si­dized, whether via TIFs (tax­in­cre­ment fi­nanc­ing for in­fra­struc­ture that, out in the coun­ties, is cus­tom­ar­ily paid for by de­vel­op­ers), PI­LOTs (pay­ments in lieu of taxes) or other tax credit pro­grams.

All Mr. Plank has done is ask for the big­gest sub­sidy yet. But he has done his math cor­rectly.

Con­sider: If we gave him a $1.2 billion check (in­stead of “free” in­fra­struc­ture), and he in­vested it at 2.5 per­cent, he’d earn in­ter­est of $30 mil­lion a year — ex­actly enough to off­set the afore­men­tioned tax hit in the city. So the re­quested sub­si­dies en­able Port Cov­ing­ton’s eco­nom­ics to make sense, at least for Mr. Plank, de­spite the city’s pun­ish­ing tax rate. But does it make sense for the city? Crit­ics on the left ar­gue that Port Cov­ing­ton will be an en­clave for the well-to-do, with lit­tle spillover ben­e­fit for poor ar­eas in dire need of re­newal. They’re speak­ing God’s truth, as well.

Part of this is ge­og­ra­phy. Mr. Plank’s baby is the most iso­lated de­vel­opable tract in the city. It might well be called Fortress Cov­ing­ton, cut off as it is from ex­ist­ing neigh­bor­hoods by water on one side, and rail­road tracks and an el­e­vated high­way on the other.

De­vel­op­ers of­ten plead for sub­si­dies by in­vok­ing a “domino ef­fect,” promis­ing that pros­per­ity here will spread there. In this case, it’s hard to imag­ine Port Cov­ing­ton’s eco­nomic domi­noes top­pling to the other side of the tracks in South Bal­ti­more, much less to the city’s des­ti­tute east and west sides.

But the big­ger prob­lem here is not ge­og­ra­phy but eco­nom­ics. Lift­ing the city’s self-im­posed bar­rier to in­vest­ment on Port Cov­ing­ton’s 266 acres does noth­ing to re­move it else­where. The same fi­nan­cial math that led Mr. Plank to de­mand his TIF will con­tinue to ap­ply in the rest of the city’s 52,000 acres; this sub­sidy will no more re­verse the city’s decades-long eco­nomic de­cline than did pre­vi­ous ones for Har­bor East or Har­bor Point. This is weak medicine at best, and ter­ri­bly in­equitable be­cause it is be­ing with­held from those most in need.

For too long, city lead­ers have dis­missed broad-based tax re­lief as unaf­ford­able. But their ea­ger em­brace of Mr. Plank’s au­da­cious re­quest it­self chal­lenges this claim.

Cut­ting the city’s prop­erty tax rate in half would, in­deed, cut re­ceipts by about $400 mil­lion this year. The con­tem­plated $1.2 billion in city, state and fed­eral sub­si­dies for Mr. Plank’s project alone would cover three years of such losses.

But, of course, with a com­pet­i­tive tax rate the city would not only be at­trac­tive to Mr. Plank but to un­told num­bers of oth­ers who would like to in­vest in Bal­ti­more but lack po­lit­i­cal mus­cle to win the con­ces­sions that would make this worth­while. The city’s tax base — its prop­erty val­ues, its piggy-back in­come taxes from new res­i­dents and much else — would grow in ex­actly the way de­scribed by Port Cov­ing­ton’s ad­vo­cates. Just much more, faster and beyond “rich en­claves.”

When San Fran­cisco’s con­fis­ca­tory prop­erty tax rate was slashed by two-thirds via Cal­i­for­nia’s Prop 13 ref­er­en­dum in the late ’70s, it had to tighten its fis­cal belt for just three years be­fore rev­enue growth from an ex­pand­ing tax base more than off­set the ini­tial losses from the vo­ter­im­posed tax cap; it soon be­came a su­per­star city.

Scof­fers say that “we’re no San Fran­cisco.” But when Prop13 kicked in, that city was los­ing pop­u­la­tion and jobs faster than Bal­ti­more. What’s pre­vent­ing a sim­i­lar re­nais­sance here is our re­fusal to do for ev­ery­one what we’re will­ing to do for Kevin Plank.